Inducing tensile stresses in the channels of n-type metal-oxide-semiconductor (NMOS) field-effect transistors (FETs) help improve the electron mobility in the channel regions. Inducing compressive stresses in the channels of p-type metal-oxide-semiconductor (PMOS) FETs help improve the hole mobility in the channel regions. With the improved carrier mobility, the drive currents of the NMOS FETs and PMOS FETs may be improved. There were various methods and structures for increasing the stresses in the NMOS and PMOS FETs, and new methods and structures are still being explored to further increase the stresses.